Sorry to dissapoint you,mate,but this song was written by Robby Krieger.
As has been stated,it is a tribute to the late Otis Redding.
I actually dig it,although it's not your "typical Doors song".
Plus,I like Robby's "Bobdylanish" voice,ha!

Song MeaningJim Morrison sings this song as a tribute to Ottis Redding who Jim had idolized. written by Robby Krieger and Jim, in their 1969 album "The Soft Parade". Morrison sings an a capella intro for the song, singing directly about Otis Redding. "Poor Otis dead and gone, "The references "Dock of the Bay", "left me here to sing his song" because in August 1967 and it Released in January 1968 after Redding's death on December 10, the charter plane which was carrying him crashed into Lake Monona, outside Madison, Wisconsin. Redding and six others were killed. Only one passenger survived, Ben Cauley of The Bar-Kays. Redding's body was recovered from the lake the day after the crash. several other references to Redding's song like songs.